VISCOELASTIC PROPERTIES OF CANINE TRACHEAL MUCUS - EFFECTS OF STRUCTURAL INHOMOGENEITIES AND STORAGE

Tracheal mucus is an inhomogeneous material and thus its viscoelastic properties may vary substantially within a mucus sample. In this study on canine tracheal mucus, we investigated this variation of mucus vis coelasticity and addressed the question whether or not the viscoelasti city is affected by storage of the mucus at low temperatures. Mucus sa mples were collected from 16 beagle dogs kept under clean air conditio ns. By means of magnetic rheometry, dynamic viscosity and elasticity w ere determined either in the fresh state of these samples or after sto rage at -80 degrees C. Owing to inhomogeneities within the gel-structu re of the mucus, local values of the viscoelastic parameters differed by more than an order of magnitude. Short storage periods (5 d) were f ound to decrease, long periods (100 d) to increase the viscosity as we ll as elasticity parameters of the mucus material. These results empha size the fact that measured viscoelastic properties of mucus are avera ge values depending on the measuring protocol. In addition, these valu es are modified by storage of the mucus at low temperatures.